Conventional chips with logic unit duplication of units that use storage arrays, such as arrays of on-chip SRAM or register files or arrays of flip-flops, necessarily duplicate the storage arrays. This allows detection of errors in address or control information that affects the location of stored data. Storage arrays use more silicon area than logic gates and individual flip-flops. What is needed is a way, in chips with logic unit duplication, to provide redundancy of address and control information without duplicating storage arrays.